Vol. 286, Issue 2, 670-675, August 1998

Prevention of Thrombosis and Enhancement of Thrombolysis in Rabbits by SR 121787, a Glycoprotein II/III Antagonist

P. Hoffmann, A. Bernat, P. Savi and J. M. Herbert

Sanofi Recherche, Haemobiology Research Department, Toulouse, France

SR 121566, a novel nonpeptide antiplatelet agent with high affinity and specificity for the GP IIb/IIIa complex, exhibits potent in vitro antiaggregating activity in rabbit platelets. This paper reports results from a study in rabbits about the efficacy and tolerability of SR 121787, the prodrug of SR 121566. After p.o. pretreatment with SR 121787, ADP-, arachidonic acid- and collagen-induced rabbit platelet aggregation was inhibited ex vivo in a dose-dependent manner (ED₅₀ between 2.3 and 6.1 mg/kg). Collagen-induced thrombocytopenia was totally abolished by SR 121787 at 20 mg/kg p.o. In a carotid artery lesion model of arterial thrombosis, p.o. administration of SR 121787 resulted in a dose-dependent inhibition of thrombosis with a maximum effect of 68% (ED₅₀ = 16.0 ± 0.3 mg/kg). Recombinant tissue plasminogen activator-induced thrombolysis of a preformed thrombus in the jugular vein was potentiated by SR 121787 at doses between 1 and 6 mg/kg i.v. In an ear incision bleeding model, SR 121787 at doses up to 15 mg/kg p.o. did not cause an increase in blood loss. These results demonstrate that SR 121787 exerts oral antiplatelet, antithrombotic and thrombolysis-enhancing efficacy in rabbits. SR 121787 appears to be a promising compound for evaluation under clinical conditions in the therapy of acute coronary syndromes.